1. Field of the Invention
This invention relates generally to circle cutting devices, and, more particularly to a circle cutting jig that mounts to the base of a router.
2. Description of the Related Art
A router is a power tool that may be used in a variety of construction, industrial, or household applications. Generally, a router is comprised of a vertical motor that is mounted on a supporting frame. The motor may include a shaft that extends in a vertical direction away from the motor. Moreover, the shaft may include a chuck located on the furthest end of the shaft. The chuck may be adapted to simplify exchanging and securing a variety of bits. These bits may be used to determine the nature of the operation the router is to perform. For example, in one application, the router may be used to make cuts in wood, and by securing the appropriate bit in the chuck, the router may be manipulated to make precise cuts in the wood material.
A plunge router may be used to make circle cuts in a variety of materials. Typically, the plunge router is supported above the material to be cut using a spring mechanism that is attached to the support frame, and by applying a downward vertical force to the router, the attached bit may be engaged with the material to be cut. Those skilled in the art will appreciate that the vertical downward movement of the plunge router may be variably controlled, and the depth of the cuts made to the work piece may be precisely determined.
The plunge router may be used to construct mortises and circular cutouts in a variety of materials. For example, the plunge router may be used to form circular tabletops, to fabricate speaker cutouts, and to make arcs or circular patterns on furniture. Those skilled in the art will appreciate that a variety of devices are available to simplify making circular cuts using the plunge router. Unfortunately, these devices are costly and difficult to use. Moreover, because of different router configurations, a device or attachment that is designed for one router may not operate properly when used with a different router. The problem may be exacerbated by the large variety of routers that are available. Furthermore, the existing devices or attachments are not adapted for working with small circles. For example, it may be necessary to make circular cuts that have a diameter that is smaller than the diameter of the supporting frame of the router. In addition, it is desirable to have the ability to make circular cuts in incremental amounts with a high degree of resolution.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
In one aspect of the present invention, a circle jig is comprised of a plate that has an escape hole and a plurality of pivot holes formed therein. The plate has a reference point, and the pivot holes are arranged on the plate in a nonlinear array at preselected locations with respect to the reference point.
In another aspect of the present invention, a method for using a circle jig is provided. The method includes attaching the circle jig to a base of a router, and determining the diameter of a circular cut. A pivot hole on the circle jig that corresponds with the diameter of the circular cut is selected. The pivot holes are positioned in a nonlinear array at precise distances from a reference point of the circle jig. The pivot hole is secured about a pivot point in a work piece, and the circle jig and the router are rotated in a circular motion around the pivot point.